Cancer is the second leading cause of death in the United States after cardiovascular disease (Boring et al. Cancer J. Clin. 43:7, 1993; incorporated herein by reference). One in three Americans will develop cancer in his or her lifetime, and one of every four Americans will die of cancer. In order to better combat this deadly disease, efforts have recently focused on fine tuning the categorization of tumors; by categorizing cancers, physicians hope to better treat an individual's cancer by providing more effective treatments. Researchers and physicians have categorized cancers based on invasion, metastasis, gross pathology, microscopic pathology, imunohistochemical markers, and molecular markers. With the recent advances in gene chip technology, researchers are increasingly focusing on the categorization of tumors based on the expression of marker genes.
The most common human cancers are malignant neoplasms of the skin (Hall et al. J. Am. Acad. Dermatol. 40:35–42, 1999; Weyers et al. Cancer 86:288–299, 1999; each of which is incorporated herein by reference). The incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease (Byers et al. Hematol. Oncol. Clin. North Am. 12:717–735, 1998; McMasters et al Ann. Surg. Oncol. 6:467–475, 1999; each of which is incorporated herein by reference). Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular, or immunohistochemical marker defines subsets of this neoplasm (Weyers et al. Cancer 86:288–299, 1999; Byers et al. Hematol. Oncol. Clin. North Am. 12:717–735, 1998; each of which is incorporated herein by reference). Accordingly, though melanoma is thought to present with different “taxonomic” forms, these are considered part of a continuous spectrum rather than discrete entities (Weyers et al Cancer 86:288–299, 1999; incorporated herein by reference). Improved characterization and understanding of this potentially deadly disease would be valuable.